$(function () {
  $(".docViewer").on("mousedown", function (event) {
    var center = {
      x: event.clientX,
      y: event.clientY
    }
    if (event.button == 0) {
      _zoom = $(".docViewer").data("zoom") + 0.15
      $(".docViewer").docview("zoomByPinch", [_zoom, center]);
    }
    else {
      _zoom = $(".docViewer").data("zoom") - 0.15
      // $(".docViewer").docview("zoomByPinch", [_zoom, center]);
    }
  })
})